Apparatus and methods for placing an additive fluid into a refrigerant circuit

ABSTRACT

A supply canister is partially filled with a refrigerant circuit additive liquid and is partially evacuated. Additive liquid from the canister may be placed into the refrigerant circuit of an air conditioning system by (1) connecting the canister to the circuit after it has been emptied and a vacuum pressure created therein, (2) connecting the canister to the refrigerant circuit suction line during system operation, or (3) connecting the canister to the suction line with the system off, to thereby force refrigerant from the circuit into the canister, and then starting the system to cause the vacuum pressure in the suction line to draw the contents of the canister into the refrigerant circuit.

This is a continuation, of application Ser. No. 09/802,178, filed Mar.8, 2001, such prior application being incorporated by reference hereinin its entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to the maintenance of airconditioning or refrigeration systems and, in a preferred embodimentthereof, more particularly relates to apparatus and methods for placingan additive fluid into the refrigerant circuit of an air conditioningsystem.

In the typical air conditioning or refrigeration system it is oftennecessary to place an additive fluid (normally a liquid) into therefrigerant circuit portion of the system to maintain the performance ofthe system at a satisfactory level. Examples of additive fluids placedin refrigerant circuits include compressor oil, stop-leak liquid, acidneutralizers, drying agents, and ultraviolet colored leak-finder liquid.

Additive fluids of these and other types are conventionally placed inrefrigerant circuits by one of four methods—namely, (1) the refrigerantcircuit is opened, and an additive liquid is simply poured into thecircuit; (2) the additive fluid is placed in a container along withpressurized refrigerant and is expelled with the pressurized refrigerantinto the circuit; (3) the additive fluid is placed in an in-line storagedevice, and pressurized refrigerant is flowed through the storage deviceto force the additive fluid into the circuit along with the pressurizedrefrigerant; or (4) the additive fluid is injected into the circuitusing a mechanical piston to force the fluid into the circuit.

These conventional techniques carry with them certain known problems,limitations and disadvantages. For example, to simply open therefrigerant circuit and pour the additive in can undesirably causerelease of refrigerant to the atmosphere, and can also undesirablyintroduce contaminating air into the circuit. Packaging an additivefluid in a container with pressurized refrigerant to be forciblyinjected into the circuit is also undesirable due the expense of addingrefrigerant to the container as a propellant, the safety concernsinherent in a pressurized container structure, and the need to match therefrigerant propellant with the type of refrigerant within the circuit.Placing the additive fluid in an in-line device requires that therefrigerant forced through the device match the refrigerant in thecircuit to avoid contamination of the circuit. Injecting additive fluidinto a refrigerant circuit using a mechanical piston device tends to bea somewhat cumbersome task requiring specialized packaging and/orequipment.

As can readily be seen from the foregoing, a need exists for improvedapparatus and methods for placing an additive fluid into a refrigerantcircuit. It is to this need that the present invention is directed.

SUMMARY OF THE INVENTION

In carrying out principles of the present invention, in accordance witha preferred embodiment thereof, a specially designed vessel or canisteris provided for use in placing an additive fluid, representatively anadditive liquid, into the refrigerant circuit of an air conditioning orrefrigeration system, representatively an automotive air conditioningsystem. In a preferred embodiment thereof, the vessel has an interiorcommunicatable with a suction line portion of the refrigerant circuit,the vessel interior being partially filled with an additive liquid,being partially evacuated to a vacuum pressure less than that of thesuction line portion during operation of the air conditioning system,and being substantially devoid of refrigerant.

According to a first method of utilizing the partially evacuated vessel,the interior of the vessel is initially communicated with the interiorof the suction line portion during operation of the air conditioningsystem, representatively using a refrigerant recharge hose assembly,whereupon the greater vacuum pressure in the suction line portion of therefrigerant circuit draws the additive liquid into the suction lineportion.

According to a second method of utilizing the partially evacuatedvessel, the refrigerant circuit is emptied and a vacuum pressure iscreated therein which is greater than the vacuum pressure within thevessel. The vessel is then communicated with the interior of therefrigerant circuit, representatively using a refrigerant recharge hoseassembly, whereupon the greater vacuum pressure within the emptiedrefrigerant circuit draws the additive fluid into the refrigerantcircuit.

According to a third method of utilizing the partially evacuated vessel,the interior of the vessel is initially communicated with the interiorof the suction line portion, representatively using a refrigerantrecharge hose assembly, while the air conditioning system is turned offand a positive pressure exists in the interior of the suction lineportion. The positive pressure within the suction line portion forcesrefrigerant therefrom into the vessel, thereby positively pressurizingits interior. Next, the air conditioning system is turned on to create anegative pressure within the suction line portion, thereby drawing therefrigerant and additive liquid from the positively pressurized canisterinterior into the suction line portion.

The provision and use of the specially designed partially evacuatedvessel provides a variety of advantages over conventional pressurizedcanisters containing refrigerant and liquid additive. For example, sincethere is no refrigerant in the vessel, the same additiveliquid-containing vessel can be used with a wide variety of airconditioning or refrigeration systems that utilize different types ofrefrigerants—the vessel does not have to be “matched” to a particulartype of refrigerant in a circuit in order to avoid contamination thereofby a different type of refrigerant within the vessel.

Moreover, since refrigerant is not packaged within the vessel, thematerial cost of the partially filled vessel is substantially reduced.Additionally, since there is no refrigerant disposed within theas-manufactured vessel it cannot leak refrigerant into the atmosphere,and the lack of pressurized refrigerant within the as-manufacturedvessel renders it safer to ship and store.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a representative air conditioningsystem into the refrigerant circuit portion of which an additive fluidis being placed using a specially designed, partially evacuated additivefluid canister embodying principles of the present invention;

FIG. 2 schematically illustrates the canister after its additive fluidhas been placed into the refrigerant circuit, with FIGS. 1 and 2together illustrating first and second methods of placing an additivefluid into the refrigerant circuit; and

FIGS. 3 and 4 are schematic diagrams similar to those in FIGS. 1 and 2and together illustrate a third method of placing an additive fluid intoa refrigerant circuit using the partially evacuated additive fluidcanister.

DETAILED DESCRIPTION

Schematically depicted in FIGS. 1 and 2 are first and second methods ofplacing an additive fluid 10 in the refrigerant circuit 12 of an airconditioning or refrigeration system which is representatively anautomotive air conditioning system 14. The additive fluid 10 isrepresentatively an additive liquid such as, for example, compressoroil, a stop-leak liquid, an ultraviolet colored leak-finder liquid, anacid neutralizer, or a drying agent.

The air conditioning system 14 is representatively of the directexpansion type and comprises the usual compressor 16, condenser 18,expansion valve 20 and evaporator 22 connected as shown in therefrigerant circuit 12. Compressor 16 is disposed between suction andliquid line portions 12 a,12 b of the circuit 12, with suction lineportion 12 a having a low side pressure tap or service fitting 24installed therein, and liquid line portion 12 b having a high sidepressure tap or service fitting 26 installed therein. During operationof the system 14, refrigerant is flowed through the circuit 12 in thedirection indicated by the circuit flow arrows in FIG. 1.

According to a key feature of the present invention, a speciallydesigned vessel or canister 28 (see FIG. 1) is partially filled with theadditive liquid 10 and is partially evacuated to a vacuum pressuresuitable for the air conditioning system with which the canister 28 isto be used (representatively in the range of from about 12″ to about 15″Hg vacuum for an automotive air conditioning system refrigerant circuit)which is (1) less than the vacuum pressure within the refrigerantcircuit suction line portion 12 a (typically in the range of from about20″ to about 30″ Hg vacuum for an automotive air conditioning systemrefrigerant circuit) during operation of the air conditioning system 14with refrigerant operatively flowing through the circuit 12, and (2)less than the positive pressure within the suction line portion 12 a(for example, about 78.4 psig when the ambient temperature is 75 degreesF.) when the air conditioning system 14 is not operating, andrefrigerant is not being flowed through the circuit 12.

As schematically depicted in FIG. 1, the partially evacuated interior 30of the canister 28, as originally fabricated, contains only the additiveliquid 10 and is devoid of refrigerant material. The canister 28 thusdiffers in two primary regards from conventional additive injectioncanisters—namely, (1) it does not contain refrigerant, and (2) itsinterior is at a substantial negative pressure as opposed to beinghighly pressurized. Canister 28 is of a suitable metal material and hasa hollow cylindrical body 32 with a lower end 34 and an upper end 36having an externally threaded tubular projection 38 thereon, theprojection 38 having a closed upper end 40.

Representatively, the refrigerant circuit 12 schematically depicted inFIG. 1 is filled with R134a refrigerant, with the suction line servicefitting 24 being of a different configuration than that of the liquidline service fitting 26. However, the principles of the presentinvention are not limited in any manner to an R134a refrigerant circuit.TO place the additive liquid 10 into the refrigerant circuit 12 using afirst method of the present invention, the interior 30 of the canister28 (see FIG. 1) is communicated with the interior of the refrigerantcircuit suction line portion 12 a, during operation of the airconditioning system 14 and flow of refrigerant through the circuit 12,using a conventional R134a refrigerant recharge hose assembly 42 whichis illustrated in phantom for purposes of illustrative clarity.

Recharge hose assembly 42 includes a quick disconnect fitting 44 (oranother type of connection fitting such as a threaded fitting)interconnected by a length of refrigerant charging hose 46 to aninternally threaded tapping/dispensing valve 48 having a rotatablehandle 50 useable to axially drive a piercing stem portion 52 of thevalve 48. To ready the canister 28 for use in placing the additiveliquid 10 into the refrigerant circuit 12, the tapping/dispensing valve48 (with its piercing stem 52 in an upwardly retracted position) isthreaded onto the tubular projection 38 of the canister 28, and thequick disconnect fitting 44 is connected to the suction line serviceport 24.

With the air conditioning system 14 running, and refrigerant beingoperatively flowed through the suction line portion 12 a at a vacuumpressure greater than that in the partially evacuated canister interior30, the tapping/dispensing valve handle 50 is operated to pierce theupper end 40 of the canister projection 38 and place the canisterinterior 30 in communication with the interior of the suction lineportion 12 a. As indicated by the arrows 54 in FIG. 1, the higher vacuumpressure in the suction line portion 12 a draws the additive liquid 10from the partially evacuated canister interior 30 into the suction lineportion 12 a, thereby emptying the canister 30 of its additive liquidcontent as shown in FIG. 2.

This higher vacuum pressure emptying of the canister 28 may befacilitated by inverting the canister 28 and holding it higher than thesuction line service fitting 24. After the additive liquid 10 is placedinto the refrigerant circuit in this manner, the refrigerant rechargehose assembly 42 is disconnected from the service fitting 24 and thecanister 28 and the now emptied canister 28 discarded.

With continued reference to FIGS. 1 and 2, a second method of utilizingthe specially designed, partially evacuated canister 28 to place itsadditive liquid 10 into the refrigerant circuit 12 is to communicate theinterior 30 of the canister 28 with the interior of the refrigerantcircuit (e.g., at its suction line portion 12 a), using the hoseassembly 42, while the refrigerant circuit 12 has been emptied forrepair and has a service vacuum pressure maintained therein which isgreater than the vacuum pressure within the interior 30 of the canister28. The service vacuum pressure within the refrigerant circuit 12 pullsthe additive liquid 10 from the canister interior 30 into therefrigerant circuit 12 as indicated by the arrows 54 in FIG. 1.

A third method of utilizing the specially designed, partially evacuatedcanister 28 to place its additive liquid 10 into the refrigerant circuit12 is schematically illustrated in FIGS. 3 and 4 to which reference isnow made. Utilizing this second method, with the air conditioning system14 initially being turned off, so that refrigerant is not being flowedthrough the circuit 12 and a positive pressure is present in theinterior of the suction line portion 12 a, the partially evacuatedcanister 28 is interconnected via the hose assembly 42 to the suctionline service fitting 24, with the tapping/dispensing valve 48 being inits closed position, as previously described. The valve handle 50 isthen rotated to axially drive the stem 52, pierce the canisterprojection 38, and initially communicate the partially evacuatedcanister interior 30 with the positively pressurized refrigerant withinthe suction line portion 12 a.

As depicted in FIG. 3, this causes positively pressurized refrigerant 56from within the interior off the suction line portion 12 a to beforcibly flowed into the partially evacuated canister interior 30 viathe hose 46, as indicated by the arrows 58 in FIG. 3, to become ineffect a carrier for the additive liquid 10. Next, the air conditioningsystem 14 is turned on to create an operative flow of refrigerant 56through the circuit 12 and generate in the suction line portion 12 a avacuum pressure. The positive pressure previously created in theinterior 30 of the canister 28 by the forcible injection of refrigerant56 thereinto causes the liquid additive and refrigerant 10,56 within thecanister interior 30 to be flowed into the suction line portion 12 a,via the hose 46, as indicated by the arrows 60 in FIG. 4, therebysubstantially emptying the canister 28 of its refrigerant and additivecontents. This transfer of refrigerant and additive to the circuit 12may be facilitated by inverting the canister 28 and positioning it at ahigher level than that of the suction line service fitting 24. Aftersuch transfer is completed, the refrigerant recharge hose assembly 42 isdisconnected from the canister 28 and the service fitting 24, and theemptied canister 28 discarded.

The provision and use of the specially designed partially evacuatedcanister 28 provides a variety of advantages over conventionalpressurized canisters containing refrigerant and liquid additive. Forexample, since there is no refrigerant in the canister, the samecanister can be used with a wide variety of air conditioning orrefrigeration systems that utilize different types of refrigerants—thecanister does not have to be “matched” to a particular type ofrefrigerant in a circuit in order to avoid contamination thereof by adifferent type of refrigerant within the canister.

Moreover, since refrigerant is not packaged within the canister, thematerial cost of the partially filled canister is substantially reduced.Additionally, since there is no refrigerant disposed within theas-manufactured canister it cannot leak refrigerant into the atmosphere,and the lack of pressurized refrigerant within the as-manufacturedcanister renders it safer to ship and store.

The foregoing detailed description is to be clearly understood as beinggiven by way of illustration and example only, the spirit and scope ofthe present invention being limited solely by the appended claims.

What is claimed is:
 1. Apparatus for use in placing an additive fluidinto a refrigerant circuit, said apparatus comprising a fluid-containingvessel structure which, prior to its first use, has a partiallyevacuated interior communicatable with the refrigerant circuit and beingpartially filled with an additive fluid, said fluid-containing vesselstructure having an internal vacuum pressure within the range of fromabout 12″ Hg to about 15″ Hg.
 2. The apparatus of claim 1 wherein saidinterior is substantially devoid of refrigerant.
 3. The apparatus ofclaim 1 wherein: the refrigerant circuit includes a suction line portionhaving, during operative flow of refrigerant therethrough, a firstvacuum pressure, and the interior vacuum pressure of saidfluid-containing vessel structure is less than said first vacuumpressure.
 4. The apparatus of claim 1 wherein: said fluid-containingvessel structure is partially filled with an additive liquid. 5.Apparatus for use in placing an additive fluid into a refrigerantcircuit including a suction line portion having, during operative flowof refrigerant therethrough, a first vacuum pressure, said apparatuscomprising a fluid-containing vessel structure which, prior to its firstuse, has an interior communicatable with the suction line portion, beingpartially filled with an additive fluid, being evacuated to a secondvacuum pressure less than said first vacuum pressure, and beingsubstantially devoid of refrigerant, said second vacuum pressure beingin the range of from about 12″ Hg to about 15″ Hg.
 6. The apparatus ofclaim 5 wherein said fluid-containing vessel structure is partiallyfilled with an additive liquid.
 7. A method of placing an additive fluidinto a refrigerant circuit, said method comprising the steps of:providing a fluid-containing vessel structure having an interiorpartially filled with an additive fluid and having a vacuum pressure inthe range of from about 12″ Hg to about 15″ Hg; and communicating therefrigerant circuit with said partially evacuated interior of saidfluid-containing vessel structure.
 8. The method of claim 7 wherein saidproviding step is performed using a fluid-containing vessel structurewith an interior substantially devoid of refrigerant.
 9. The method ofclaim 7 wherein said providing step is performed using afluid-containing vessel structure partially filled with an additiveliquid.
 10. The method of claim 7 wherein said communicating step isperformed by operatively interconnecting a refrigerant recharge hoseassembly between said fluid-containing vessel structure and saidrefrigerant circuit.
 11. The method of claim 7 wherein: said refrigerantcircuit includes a suction line portion which, during operative flow ofrefrigerant therethrough, has a vacuum pressure greater than the vacuumpressure within said fluid-containing vessel structure, and saidcommunicating step includes the step of communicating said partiallyevacuated interior of said fluid-containing vessel structure with theinterior of said suction line portion, during operative flow ofrefrigerant therethrough, in a manner flowing said additive fluid intosaid suction line portion.
 12. The method of claim 7 wherein: saidrefrigerant circuit has a suction line portion, said suction lineportion, during operative flow of refrigerant therethrough, having avacuum pressure greater than the vacuum pressure within saidfluid-containing vessel structure, said suction line portion, in theabsence of an operative flow of refrigerant flow therethrough, having apositive pressure, said communicating step is performed by communicatingsaid partially evacuated interior of said fluid-containing vesselstructure with the interior of said suction line portion, during anabsence of operative refrigerant flow therethrough, to thereby forcerefrigerant from said refrigerant circuit into said fluid-containingvessel structure, and said method further comprises the step, performedafter said communicating step, of creating an operative flow ofrefrigerant through said suction line portion to thereby drawrefrigerant and additive fluid into said refrigerant circuit from withinsaid fluid-containing vessel structure.
 13. A method of placing anadditive fluid into a refrigerant circuit, said method comprising thesteps of: providing a fluid-containing vessel structure having apartially evacuated interior partially filled with an additive fluid;and communicating the refrigerant circuit with said partially evacuatedinterior of said fluid-containing vessel structure, said method furthercomprising the steps, performed prior to said communicating step, ofemptying said refrigerant circuit and creating in the emptiedrefrigerant circuit a vacuum pressure greater than the vacuum pressurewithin said partially evacuated interior of said fluid-containing vesselstructure.
 14. A method of placing an additive liquid into a refrigerantcircuit, said method comprising the steps of: providing afluid-containing vessel structure which, prior to its first use, has apartially evacuated interior partially filled with an additive liquidand being substantially devoid of refrigerant, the interior having avacuum pressure in the range of from about 12″ Hg to about 15″ Hg; andcommunicating the interior of said refrigerant circuit with saidpartially evacuated interior of said fluid-containing vessel structure.15. The method of claim 14 said communicating step is performed byoperatively interconnecting a refrigerant recharge hose assembly betweensaid fluid-containing vessel structure and said suction line portion.16. The method of claim 14 wherein: said refrigerant circuit has asuction line portion which, during operative flow of refrigerant flowtherethrough, has a vacuum pressure greater than the vacuum pressurewithin said fluid-containing vessel structure, and said communicatingstep is performed by communicating the interior of said suction lineportion with said partially evacuated interior of said fluid-containingvessel structure during operative flow of refrigerant through saidsuction line portion.
 17. The method of claim 14 wherein: saidrefrigerant circuit has a suction line portion which, during operativeflow of refrigerant therethrough, has a vacuum pressure greater than thevacuum pressure within said fluid-containing vessel structure, saidsuction line portion, in the absence of an operative flow Of refrigerantflow therethrough, has a positive pressure, said communicating step isperformed by communicating said partially evacuated interior of saidfluid-containing vessel structure with the interior of said suction lineportion, during an absence of operative refrigerant flow therethrough,to thereby force refrigerant from said refrigerant circuit into saidfluid-containing vessel structure, and said method further comprises thestep, performed after said communicating step, of creating an operativeflow of refrigerant through said suction line portion to thereby drawrefrigerant and additive fluid into said refrigerant circuit from withinsaid fluid-containing vessel structure.
 18. A method of placing anadditive liquid into a refrigerant circuit, said method comprising thesteps of: providing a fluid-containing vessel structure which, prior toits first use, has a partially evacuated interior partially filled withan additive liquid and being substantially devoid of refrigerant, andcommunicating the interior of said refrigerant circuit with saidpartially evacuated interior of said fluid-containing vessel structure,said method further comprising the steps, performed prior to saidcommunicating step, of emptying said refrigerant circuit and creating inthe emptied refrigerant circuit a vacuum pressure greater than thevacuum pressure within said partially evacuated interior of saidfluid-containing vessel structure.